Characteristics of Physical and Biochemical Parameters within Mesoscale Eddies in the Southern Ocean

Abstract. Using satellite sea surface temperature (SST) and chlorophyll-a (Chl-a) as well as observation‑based reconstruction of dissolved inorganic carbon (DIC) and partial pressure of CO₂ (pCO₂) from 1996 to 2015, we analyzed the composite patterns of physical and biochemical variables over eddies in the Southern Ocean (SO). Interestingly, eddy modulation of pCO₂ has marked seasonal and regional variations. The DIC effect dominates the pCO₂ anomalies in winter. In summer, the pCO₂ anomalies within eddies are dominated by DIC (SST) anomalies in regions with larger (smaller) magnitudes of DIC anomalies. In addition, about 1/4 of eddies are observed to be abnormal (cold anticyclonic and warm cyclonic eddies) in the SO, which show opposite SST signatures contrary to normal eddies (warm anticyclonic and cold cyclonic eddies). The modification of abnormal eddies to physical and biochemical parameters is non-negligible and differs from normal eddies due to the common effects of eddy pumping and eddy-induced Ekman pumping. For example, DIC anomalies in normal and abnormal eddies show dipole patterns with opposite signals. Besides, the contributions of abnormal eddies to pCO₂ are about 2.7 times higher than normal eddies in regions where abnormal eddies dominate. However, Chl-a anomalies in normal and abnormal eddies show similar patterns with the same signals since they are dominated by eddy stirring and pumping.